sedimentary
Gravel and River Pebbles
Unconsolidated rock fragments / Detrital sediment
Hardness varies by mineral composition (typically Mohs 6-7 for quartz-rich pebbles); diverse colors including brown, tan, gray, and white; vitreous to dull luster; varied shapes from angular to rounded.
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Physical properties
Hardness varies by mineral composition (typically Mohs 6-7 for quartz-rich pebbles); diverse colors including brown, tan, gray, and white; vitreous to dull luster; varied shapes from angular to rounded.
Formation & geological history
Formed through weathering and erosion of larger parent rocks, followed by transport and rounding via water in rivers, streams, or glacial environments over thousands to millions of years.
Uses & applications
Used extensively in construction, concrete aggregate, landscaping, road surfacing, and pathway paving.
Geological facts
River gravel is naturally rounded due to the process of abrasion as rocks collide with each other while being transported downstream by flowing water.
Field identification & locations
Found abundantly in riverbeds, alluvial fans, beaches, and glacial outwash plains worldwide. Useful in geology for determining the local lithology of a watershed.
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